User Equipment, Network Node and Methods Therein for Determining a Transport Block Size in Downlink Transmissions in a Telecommunications System

ABSTRACT

A method in a user equipment ( 121 ) for determining a transport block size is provided. The transport block size is used by the user equipment ( 121 ) in receiving downlink data transmissions from a network node ( 110 ) on an enhanced Control Channel, eCCH. The user equipment ( 121 ) and the network node ( 110 ) are comprised in a telecommunications system ( 100 ). The user equipment ( 121 ) has access to a table or predetermined transport block sizes. The user equipment ( 121 ) may calculate an indicator based on the total number of PRBs allocated to the downlink data transmission N PRB , and based on an PRB offset value O PRB  or a PRB adjustment factor APRB. Then, the user equipment ( 121 ) may determine the transport block size from the table of predetermined transport block sizes based on at least the calculated indicator N PRB . A user equipment, a method in network node and a network node are also provided.

TECHNICAL FIELD

Embodiments herein relate to a network node, a user equipment andmethods therein. In particular, embodiments herein relate to determininga transport block size of downlink transmissions in a telecommunicationssystem.

BACKGROUND

In today's radio communications networks a number of differenttechnologies are used, such as Long Term Evolution (LTE), LTE-Advanced,Wideband Code Division Multiple Access (WCDMA), Global System for Mobilecommunications/Enhanced Data rate for GSM Evolution (GSM/EDGE),Worldwide Interoperability for Microwave Access (WiMax), or Ultra MobileBroadband (UMB), just to mention a few possible technologies for radiocommunication. A radio communications network comprises radio basestations providing radio coverage over at least one respectivegeographical area forming a cell. The cell definition may alsoincorporate frequency bands used for transmissions, which means that twodifferent cells may cover the same geographical area but using differentfrequency bands. User equipments (UE) are served in the cells by therespective radio base station and are communicating with respectiveradio base station. The user equipments transmit data over an air orradio interface to the radio base stations in uplink (UL) transmissionsand the radio base stations transmit data over an air or radio interfaceto the user equipments in downlink (DL) transmissions.

Long Term Evolution (LTE) is a project within the 3rd GenerationPartnership Project (3GPP) to evolve the WCDMA standard towards thefourth generation (4G) of mobile telecommunication networks. Incomparisons with third generation (3G) WCDMA, LTE provides increasedcapacity, much higher data peak rates and significantly improved latencynumbers. For example, the LTE specifications support downlink data peakrates up to 300 Mbps, uplink data peak rates of up to 75 Mbit/s andradio access network round-trip times of less than 10 ms. In addition,LTE supports scalable carrier bandwidths from 20 MHz down to 1.4 MHz andsupports both Frequency Division Duplex (FDD) and Time Division Duplex(TDD) operation.

LTE technology is a mobile broadband wireless communication technologyin which transmissions are sent using orthogonal frequency divisionmultiplexing (OFDM), wherein the transmissions are sent from basestations, also referred to herein as network nodes or eNBs, to mobilestations, also referred to herein as user equipments or UEs. Thetransmission OFDM splits the signal into multiple parallel sub-carriersin frequency.

A basic unit of transmission in LTE is a Resource Block (RB) which inits most common configuration comprises 12 subcarriers and 7 OFDMsymbols in one time slot. A unit of one subcarrier and 1 OFDM symbol isreferred to as a resource element (RE), as shown in FIG. 1. Thus, an RBcomprises 84 REs.

Accordingly, a basic LTE downlink physical resource may thus be seen asa time-frequency grid as illustrated in FIG. 1, where each ResourceElement (RE) corresponds to one OFDM subcarrier during one OFDM symbolinterval. A symbol interval comprises a cyclic prefix (cp), which cp isa prefixing of a symbol with a repetition of the end of the symbol toact as a guard band between symbols and/or facilitate frequency domainprocessing. Frequencies for subcarriers having a subcarrier spacing Δfare defined along an z-axis and symbols are defined along an x-axis.

In the time domain, LTE downlink transmissions are organized into radioframes of 10 ms, each radio frame comprising ten equally-sizedsub-frames, #0-#9, each with a T_(sub-frame)=1 ms of length in time asshown in FIG. 2. Furthermore, the resource allocation in LTE istypically described in terms of resource blocks, where a resource blockcorresponds to one slot of 0.5 ms in the time domain and 12 subcarriersin the frequency domain. Resource blocks are numbered in the frequencydomain, starting with resource block 0 from one end of the systembandwidth.

An LTE radio sub-frame is composed of multiple RBs in frequency with thenumber of RBs determining the bandwidth of the system and two slots intime, as shown in FIG. 3. Furthermore, the two RBs in a sub-frame thatare adjacent in time may be denoted as an RB pair.

Downlink transmissions are dynamically scheduled in the current downlinksubframe. This means that, in each subframe, the network node transmitscontrol information about to which UEs data is transmitted, and uponwhich resource blocks the data is transmitted. This control signallingis typically transmitted in the first 1, 2, 3 or 4 OFDM symbols in eachsubframe denoted the control region. In FIG. 3, for example, a downlinksystem with 1 out of 3 possible OFDM symbols as control signalling isillustrated.

The dynamic scheduling information is communicated to the UEs via aPhysical Downlink Control CHannel (PDCCH) transmitted in the controlregion. After successful decoding of a PDCCH, the UE performs receptionof the Physical Downlink Shared CHannel (PDSCH) or transmission of thePhysical Uplink Shared CHannel (PUSCH) according to a pre-determinedtiming specified in the LTE specification.

Furthermore, LTE uses Hybrid-ARQ (HARQ). That is, after receiving DLdata in a subframe, the UE attempts to decode it and reports to thenetwork node an Acknowledgement (ACK) or a Non-Acknowledgement (NACK) ifthe decoding was successful or not successful. This is performed via thePhysical Uplink Control CHannel (PUCCH). In case of an unsuccessfuldecoding attempt, the network node may retransmit the erroneous data.

Similarly, the network node may indicate to the UE an Acknowledgement(ACK) or a Non-Acknowledgement (NACK) if the decoding of the PUSCH wassuccessful or not successful via the Physical Hybrid ARQ IndicatorCHannel (PHICH).

The DL Layer-1/Layer 2 (L1/L2) control signalling transmitted in thecontrol region comprises the following different physical-channel types:

-   -   The Physical Control Format Indicator CHannel (PCFICH). This        informs the UE about the size of the control region, e.g. one,        two, or three OFDM symbols for system bandwidths larger than 10        RBs and two, three or four OFDM symbols for system bandwidths        equal to 10 RBs or smaller. There is one and only one PCFICH on        each component carrier or, equivalently, in each cell.    -   The Physical Downlink Control CHannel (PDCCH). This is used to        signal DL scheduling assignments and UL scheduling grants. Each        PDCCH typically carries signalling for a single UE, but can also        be used to address a group of UEs. Multiple PDCCHs can exist in        each cell.    -   The Physical Hybrid-ARQ Indicator CHannel (PHICH). This is used        to signal hybrid-ARQ acknowledgements in response to UL-SCH        transmissions. Multiple PHICHs can exist in each cell.

These physical channels are organized in units of Resource Element Group(REG), which comprises four closely spaced resource elements. The PCFICHoccupies four REGs and a PHICH group occupies three REGs. An example ofcontrol channels in an LTE control region, assuming a system bandwidthof 8 RBs, is shown in FIG. 4.

Physical Downlink Control CHannel (PDCCH)

The PDCCH is used to carry Downlink Control Information (DCI), such as,e.g. scheduling decisions and power-control commands. More specifically,the DCI comprises:

-   -   Downlink scheduling assignments. These may comprise PDSCH        resource indication, transport format, hybrid-ARQ information,        and control information related to spatial multiplexing (if        applicable). A downlink scheduling assignment also comprises a        command for power control of the PUCCH used for transmission of        hybrid-ARQ acknowledgements in response to downlink scheduling        assignments.    -   Uplink scheduling grants. These comprise PUSCH resource        indication, transport format, and hybrid-ARQ-related        information. An uplink scheduling grant also comprises a command        for power control of the PUSCH.    -   Power-control commands for a set of UEs, which may serve as a        complement to the commands comprised in the scheduling        assignments/grants.

As multiple UEs may be scheduled simultaneously, on both DL and UL,there must be a possibility to transmit multiple scheduling messageswithin each subframe. Each scheduling message is transmitted on aseparate PDCCH, and consequently there are typically multiplesimultaneous PDCCH transmissions within each cell. To accommodatemultiple UEs, LTE defines so-called search spaces. The search spacesdescribe the set of CCEs which the UE is supposed to monitor forscheduling assignments/grants relating to a certain component carrier. AUE has multiple search spaces, namely, UE-specific search spaces and thecommon search space.

Past link adaptation to a fading channel condition is used in radiocommunication network to enhance system throughput capacity, as well as,user experience and quality of services. An important factor in theworking of fast link adaptation is the timely update of channelconditions that is fed back from the receiver to the transmitter. Thefeedback may take on several related forms, such as, e.g. a signal tonoise ratio (SNR), a signal to interference and noise ratio (SINR), areceived signal level (e.g. power or strength), supportable data rates,supportable combination of modulation and coding rates, supportablethroughputs, etc. The information may also pertain to entire frequencybands, as in W-CDMA systems, or specific portions of it as made possibleby systems based OFDM such as the LTE system. These feedback messagesmay generally be referred to as a Channel Quality Indicator (CQI).

In DL data operations in LTE, the CQI messages are fed back from the UEto the network node to assist the transmitter in the network node in thedecision of radio resource allocation. The feedback information may, forexample, be used to determine transmission scheduling among multiplereceivers; to select suitable transmission schemes, such as, e.g. thenumber of transmit antennas to activate; to allocate appropriate amountof bandwidth; and to form supportable modulation and coding rate for theintended receiver in the UE.

In UL data operations in LTE, the network node may estimate the channelquality from the Demodulation Reference Symbols (DRS) or SoundingReference Symbols (SRS) transmitted by the UEs.

The range of a CQI message in LTE is shown in the CQI message table ofFIG. 5. This table is the table 7.2.3-1 present in the standardspecification 3GPP TS 36.213 “Physical Layer Procedures”. This CQImessage table has been specifically designed to support Modulation andCoding Scheme (MCS) adaptation over wide-band wireless communicationchannels. The transition points from a lower-order modulation to ahigher-order modulation have been verified with extensive linkperformance evaluation. These specific transition points betweendifferent modulations thus provide a guideline for well-adjusted systemoperation.

Based on the CQI message from a UE, a network node may choose the bestMCS to transmit data on the PDSCH. The MCS information is conveyed tothe selected UE in a 5-bit “modulation and coding scheme” field(I_(MCS)) of the DCI, as shown in the MCS table of FIG. 6. The MCS fieldI_(MCS) signals to the UE both the modulation Q_(m) and the transportblock size (TBS) index I_(TBS). In conjunction with the total number ofallocated RBs, the TBS index I_(TBS) further determines the exacttransport block size used in the PDSCH transmission. The last three MCSentries are for HARQ retransmissions and, hence, the TBS remains thesame as the original transmission.

The specific TBSs for different number of allocated radio blocks aredefined and listed for the single layer transmission case in the TBStable 7.1.7.2.1-1, i.e. a large 27*110 table, in the standardspecification 3GPP TS 36.213 “Physical Layer Procedures”. However, theseTBSs are designed to achieve spectral efficiencies matching the CQImessages. More specifically, the TBSs are selected to achieve thespectral efficiencies shown in the table of FIG. 7.

Note that the CQI message table in FIG. 5 and, consequently, the MCStable of FIG. 6, are both designed based on the assumption that 11 OFDMsymbols are available for PDSCH transmission. This means that when theactual number of available OFDM symbols for PDSCH is different than 11,the spectral efficiency of the transmission will deviate from thespectral efficiencies shown in the table of FIG. 7.

Enhanced Control Channel (eCCH)

Transmission of a Physical Downlink Shared CHannel (PDSCH) to UEs mayuse REs in RB pairs that are not used for control messages or RS.Further, the PDSCH may either be transmitted using the UE-specificreference symbols or the CRS as a demodulation reference, depending onthe transmission mode. The use of UE-specific RS allows a multi-antennanetwork node to optimize the transmission using pre-coding of both dataand reference signals being transmitted from the multiple antennas sothat the received signal energy increases at the UE. Consequently, thechannel estimation performance is improved and the data rate of thetransmission could be increased.

In LTE Release 10, a Relay Physical Downlink Control CHannel is alsodefined and denoted R-PDCCH. The R-PDCCH is used for transmittingcontrol information from network node to Relay Nodes (RN). The R-PDCCHis placed in the data region, hence, similar to a PDSCH transmission.The transmission of the R-PDCCH may either be configured to use CRS toprovide wide cell coverage, or RN specific reference signals to improvethe link performance towards a particular RN by precoding, similar tothe PDSCH with UE-specific RS. The UE-specific RS is in the latter caseused also for the R-PDCCH transmission. The R-PDCCH occupies a number ofconfigured RB pairs in the system bandwidth and is thus frequencymultiplexed with the PDSCH transmissions in the remaining RB pairs, asshown in FIG. 8.

FIG. 8 shows a downlink sub-frame showing 10 RB pairs and transmissionof 3 R-PDCCH, that is, red, green or blue, of size 1 RB pair each. TheR-PDCCH does not start at OFDM symbol zero to allow for a PDCCH to betransmitted in the first one to four symbols. The remaining RB pairs maybe used for PDSCH transmissions.

In LTE Release 11 discussions, attention has turned to adopt the sameprinciple of UE-specific transmission as for the PDSCH and the R-PDCCHfor enhanced control channels, that is, including PDCCH, PHICH, PBCH,and Physical Configuration Indication CHannels (PCFICH). This may bedone by allowing the transmission of generic control messages to a UEusing such transmissions to be based on UE-specific reference signals.This means that precoding gains may be achieved also for the controlchannels. Another benefit is that different RB pairs may be allocated todifferent cells or different transmission points within a cell. Thereby,inter-cell interference coordination between control channels may beachieved. This frequency coordination is not possible with the PDCCH,since the PDCCH spans the whole bandwidth.

FIG. 9 shows an enhanced PDCCH (ePDCCH) which, similar to the CCE in thePDCCH, is divided into multiple groups (eREG) and mapped to one of theenhanced control regions. However, it should be noted that the relationbetween ePDCCH, eREGs and REs is not yet determined in the 3GPPstandard. One option could be that the relation between ePDCCH andeREGs/REs are to be similar to that as for PDCCH, i.e. that one ePDCCHis divided into one or multiple eCCE(s) corresponding to 36 REs, whichin turn is divided into 9 eREGs each comprising 4 REs. Another optionmay be to have one eCCE corresponding to up to 36 REs, and wherein eacheREG corresponds to 18 REs. According to yet another option, it may bedecided that the eCCE should correspond to even more than 36 REs, suchas, e.g. 72 or 74.

That is, FIG. 9 shows a downlink sub-frame showing a CCE belonging to anePDCCH that is mapped to one of the enhanced control regions, to achievelocalized transmission.

Note that, in FIG. 9, the enhanced control region does not start at OFDMsymbol zero, to accommodate simultaneous transmission of a PDCCH in thesub-frame. However, as was mentioned above, there may be carrier typesin future LTE releases that do not have a PDCCH, in which case theenhanced control region could start from OFDM symbol zero within thesub-frame.

Time Division Duplex (TDD)

Transmission and reception from a UE may be multiplexed in the frequencydomain, in the time domain or in a combination of the two domains, suchas, e.g. the half-duplex FDD. FIG. 10 shows an illustration of FrequencyDivision Duplex (FDD) and Time Division Duplex (TDD).

Frequency Division Duplex (FDD) implies that DL and UL transmissionstake place in different, sufficiently separated, frequency bands, whileTime Division Duplex (TDD) implies that DL and UL transmissions takeplace in different, non-overlapping time slots. Thus, TDD may operate inan unpaired spectrum, whereas FDD requires a paired spectrum.

Typically, the structure of the transmitted signal is organized in theform of a frame structure. For example, LTE uses ten equally-sizedsubframes of length 1 ms per radio frame as illustrated in FIGS. 2 and11.

As shown in the upper part of FIG. 11, in case of FDD operation, thereare two carrier frequencies; one carrier frequency for UL transmission(F_(UL)) and one carrier frequency for DL transmission (F_(DL)). Atleast with respect to the UE, FDD may either be full duplex or halfduplex. In the full duplex case, a UE may transmit and receivesimultaneously, while in half-duplex operation, the UE cannot transmitand receive simultaneously. However, it should be noted that the networknode is capable of simultaneous reception or transmission, e.g.receiving from one UE while simultaneously transmitting to another UE.In LTE, a half-duplex UE is monitoring or receiving in the DL exceptwhen explicitly being instructed to transmit in a certain subframe.

As shown in the lower part of FIG. 11, in case of TDD operation, thereis only a single carrier frequency, and UL and DL transmissions arealways separated in time and also on a cell basis. As the same carrierfrequency is used for UL and DL transmission, both the network node andthe UEs need to switch from transmission to reception and vice versa. Animportant aspect of any TDD system is to provide the possibility for asufficiently large guard time, where neither DL nor UL transmissionsoccur. This is required in order to avoid interference between UL and DLtransmissions. For LTE, this guard time is provided by specialsubframes, e.g. subframe #1 and, in some cases, subframe #6. These arethen split into three parts: a downlink part (DwPTS), a guard period(GP), and an uplink part (UpPTS). The remaining subframes are eitherallocated to UL or DL transmission.

TDD allows for different asymmetries in terms of the amount of resourcesallocated for UL and DL transmission, respectively, by means ofdifferent UL and DL configurations. As shown in FIG. 12, there are sevendifferent configurations in LTE. It should be noted that a DL subframemay mean either a DL subframe or the special subframe.

The LTE system has been designed to support a wide range of operationmodes comprising the FDD and the TDD modes. Each of these modes may alsooperate with normal cyclic prefix (CP) lengths for typical cell sizes orwith extended CP lengths for large cell sizes. To facilitate DL to ULswitching, some special TDD subframes are configured to transmit userdata in the DwPTS with shortened duration.

Furthermore, in the LTE system, available resources may be dynamicallyappropriated between control information and user data information. Forexample, the radio resource in a normal subframe is organized into 14OFDM symbols. The LTE system may dynamically use {0, 1, 2, 3} OFDMsymbols or {0, 2, 3, 4} OFDM symbols in case of very small systembandwidths to transmit control information. As a result, the actualnumber of OFDM symbols available for data transmission is 14, 13, 12, 11or 10.

A summary of the number of available OFDM symbols for PDSCH transmissionin different operation modes is given in the table of FIG. 13.

As previously mentioned, the CQI message table in FIG. 5 and,consequently, the MCS table of FIG. 6, are both designed based on theassumption that 11 OFDM symbols are available for PDSCH transmission. Asshown in the table in FIG. 13, there are many cases where the actualresource available for transmission does not match this assumption.Thus, this assumption may lead to mismatch problems when the actualnumber of OFDM symbols available for PDSCH deviates from the assumed 11OFDM symbols, which consequently will reduce data throughput.

SUMMARY

It is an object of embodiments herein to provide increased datathroughput in a telecommunications system.

According to a first aspect of embodiments herein, the object isachieved by a method in a user equipment for determining a transportblock size. The transport block size is used by the user equipment inreceiving downlink data transmissions from a network node on an enhancedControl Channel, eCCH. The user equipment and the network node arecomprised in a telecommunications system. The user equipment has accessto a table of predetermined transport block sizes. The user equipmentcalculates an indicator N_(PRB) based on the total number of PRBsallocated to the downlink data transmission N′_(PRB), and based on anPRB offset value O_(PRB) or a PRB adjustment factor A_(PRB). Then, theuser equipment determines the transport block size from the table ofpredetermined transport block sizes based on at least the calculatedindicator N_(PRB).

According to a second aspect of embodiments herein, the object isachieved by a user equipment for determining a transport block size. Thetransport block size is used by the user equipment in receiving downlinkdata transmissions from a network node on an enhanced Control CHannel,eCCH. The user equipment and the network node are comprised in atelecommunications system. The user equipment has access to a table ofpredetermined transport block sizes. The user equipment comprises aprocessing circuitry configured to calculate an indicator N_(PRB) basedon the total number of PRBs allocated to the downlink data transmissionN′_(PRB), and based on an PRB offset value O_(PRB) or a PRB adjustmentfactor A_(PRB). The processing circuitry is further configured todetermine the transport block size from the table of predeterminedtransport block sizes based on at least the calculated indicatorN_(PRB).

According to a third aspect of embodiments herein, the object isachieved by a method in a network node for determining a transport blocksize. The transport block size is used by the network node intransmitting downlink data transmissions to the user equipment on anenhanced control channel, eCCH. The network node and the user equipmentare comprised in a telecommunications system. The network node hasaccess to a table of predetermined transport block sizes. The networknode calculates an indicator N_(PNB) based on the total number of PRBsallocated to the downlink data transmission N′_(PRB), and based on anPRB offset value O_(PRB), or a PRB adjustment factor A_(PRB). Then, thenetwork node determines the transport block size from the table ofpredetermined transport block sizes based on at least the calculatedindicator N_(PRB).

According to a fourth aspect of embodiments herein, the object isachieved by a network node for determining a transport block size. Thetransport block size is used by the network node in transmittingdownlink data transmissions to the user equipment on an enhanced controlchannel, eCCH. The network node and the user equipment are comprised ina telecommunications system. The network node has access to a table ofpredetermined transport block sizes. The network node comprises aprocessing circuitry configured to calculate an indicator N_(PRB) basedon the total number of PRBs allocated to the downlink data transmissionN′_(PRB), and on an PRB offset value O_(PRB), or a PRB adjustment factorA_(PRB). The processing circuitry is further configured to determine thetransport block size from the table of predetermined transport blocksizes based on at least the calculated indicator N_(PRB).

When the actual number of OFDM symbols for the downlink datatransmissions on an eCCH deviates from the assumed 11 OFDM symbols, thenumber of suitable modulation and coding schemes (MCSs) generatingsuitable code rates for the downlink data transmissions will besignificantly smaller. By including a PRB offset value O_(PRB), or PRBadjustment factor A_(PRB), in the determining of the transport blocksize as described above, the user equipment avoids unsuitable modulationand coding schemes. This enables a better scheduling of the downlinkdata transmissions on the eCCH, since unsuitable code rates, which e.g.may cause the downlink data transmissions to fail and be in need ofbeing retransmitted, is avoided.

Hence, a way of increasing data throughput in a telecommunicationssystem is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the embodiments willbecome readily apparent to those skilled in the art by the followingdetailed description of exemplary embodiments thereof with reference tothe accompanying drawings, wherein:

FIG. 1 is a schematic block diagram of a LTE downlink physical resource,

FIG. 2 is a schematic overview depicting radio frames,

FIG. 3 is a schematic overview depicting a DL sub-frame,

FIG. 4 is a schematic overview depicting control channels in an LTEcontrol region,

FIG. 5 shows a 4-bit CQI message table for LTE,

FIG. 6 shows a modulation and TBS index table (MCS table) for LTE PDSCH,

FIG. 7 shows a table depicting spectral efficiency for LTE with 11 OFDMsymbols for PDSCH,

FIG. 8 is a schematic overview depicting a DL sub-frame comprising arelay control channel,

FIG. 9 is a schematic overview depicting a DL sub-frame comprising a CCEbelonging to a ePDCCH,

FIG. 10 is a schematic overview depicting Frequency Division Duplex(FDD) and Time Division Duplex (TDD),

FIG. 11 is a schematic overview depicting a frame structure in time andfrequency for LTE in case of Frequency Division Duplex (FDD) and TimeDivision Duplex (TDD),

FIG. 12 is a schematic overview depicting different configurations forLTE in case of Time Division Duplex (TDD),

FIG. 13 shows a table depicting the available number of OFDM symbols forPDSCH for different operation modes in LTE,

FIG. 14 shows a table depicting the code rate with different number ofOFDM symbols for the PDSCH in LTE FDD or TDD non-special subframes,

FIG. 15 shows a table depicting the code rate with different number ofOFDM symbols for the PDSCH in LTE TDD special subframes,

FIG. 16 is a schematic block diagram illustrating embodiments in atelecommunications system,

FIG. 17 is a flowchart depicting embodiments of a method in a userequipment,

FIG. 18 is a flowchart depicting embodiments of a method in a networknode,

FIG. 19 is a schematic block diagram of embodiments of a network node,

FIG. 20 is a schematic block diagram of embodiments of a user equipment.

DETAILED DESCRIPTION

The figures are schematic and simplified for clarity, and they merelyshow details which are essential to the understanding of theembodiments, while other details have been left out. Throughout, thesame reference numerals are used for identical or corresponding parts orsteps.

As part of the developing the embodiments described herein, a problemwill first be identified and discussed.

In some scenarios, it has been noticed that one way to deal with theobvious mismatch of OFDM symbols in TDD special subframes has beenintroduced into the standard specification 3GPP TS 36.213 “PhysicalLayer Procedures”.

Normally, for a downlink subframe, the user equipment first calculatesthe total number of allocated PRBs. The total number of allocated PRBsis based on the PRB resource allocation comprised in the downlinkcontrol and the procedure provided in the standard specification 3GPP TS36.213 “Physical Layer Procedures”. The total number of allocated PRBsis denoted as N′_(PRB).

Then, the transport block size (TBS) is determined by usingN_(PRB)=N′_(PRB) as the column indicator in the TBS Table 7.1.7.2.1-1 inthe standard specification 3GPP TS 36.213 “Physical Layer Procedures”.The column indicator indicates which column in the TBS table to look inwhen determining the TBS.

Here, however, if the transport block is transmitted in DwPTS of the TDDspecial subframe in the frame structure, the TBS is instead determinedby the UE by using

N _(PRB)=max{└N′ _(PRB)×0.75┘,1}

as the column indicator for which column to use in the TBS Table7.1.7.2.1-1 in the standard specification 3GPP TS 36.213 “Physical LayerProcedures”.

Unfortunately, this does not fully address the mismatch problems whenthe actual number of OFDM symbols available for PDSCH deviates from theassumed 11 OFDM symbols, which consequently will reduce data throughput.

This is shown by the tables of FIGS. 14-15. FIG. 14 shows the code ratewith different number of OFDM symbols for the PDSCH in LTE FDD or TDDnon-special subframes, i.e. for a normal downlink subframe. FIG. 15shows the code rate with different number of OFDM symbols for the PDSCHin LTE TDD special subframes, e.g. DwPTS.

According to one aspect, it has been observed from the tables of FIGS.14-15 that the code rate becomes excessively high when the actual numberof OFDM symbols for PDSCH is substantially less than the assumed 11symbols. These cases are indicated by the areas 141, 151 in the tablesof FIGS. 14-15. Since the user equipment will not be able to decode suchhigh code rates, transmissions based on these indicated MCSs will failand retransmissions will be needed.

According to another aspect, it has also been observed that with themismatch of radio resource assumption, code rates for some of the MCSsdeviate out of a suitable range for the wideband wireless system. Basedon extensive link performance evaluation, the CQI message table in FIG.5 has been designed based on that the code rates for QPSK and 16 QAMshould not be higher than 0.70, and that the code rates for 16 QAM and64 QAM should not be lower than 0.32 and 0.40, respectively. Asindicated by the areas 142, 152 in the tables of FIGS. 14-15, in somecases, some of the MCSs will result in a sub-optimal, or less suitable,code rate.

According to a further aspect, it has also been observed that in thecase of eCCH, a certain number of PRBs are allocated to carry the eCCH.In a low-load scenario, the network node may also schedule a single userequipment to allow peak data rate service for the user equipment. Sincethe eCCH for this user equipment may occupy at least one PRB, the userequipment cannot be allocated of all downlink PRBs. Since the LTEspecifications allow the use of the largest TBS only in conjunction withallocating all downlink PRBs to the user equipment, peak data rateservices cannot be provided if an eCCH is deployed. It may therefore beseen that, in the prior art, when the actual number of OFDM symbols forPDSCH deviates from the assumed 11 OFDM symbols, data throughput will bereduced.

Hence, when the actual number of OFDM symbols for the downlink datatransmissions on an eCCH deviates from the assumed 11 OFDM symbols, thenumber of suitable modulation and coding schemes (MCSs) generatingsuitable code rates for the downlink data transmissions will besignificantly smaller. Thus, in these cases, the transport block sizesnormally selected by the user equipment based on the total number ofPRBs allocated to a downlink data transmission may cause unsuitablemodulation and coding schemes (MCSs) to be selected and used for thedownlink data transmission. Using such unsuitable modulation and codingschemes may, for example, generate such high code rates in the downlinkdata transmissions that the downlink data transmissions will fail andretransmissions be needed. This will reduce data throughput in thetelecommunications system.

Advantageously, since data throughput is reduced when downlink datatransmissions are based on these unsuitable or sub-optimal code rates,the scheduling implementation in the network node and in the userequipment described in at least some of the embodiments herein avoidsusing any of the MCSs indicated in the areas 151, 152, 161 and 162 shownin the tables of FIGS. 14-15 for the indicated number of OFDM symbols inits downlink data transmissions.

This is performed by instead including a PRB offset value O_(PRB), orPRB adjustment factor A_(PRB), in the determining of the transport blocksize. This means that the user equipment avoids these unsuitablemodulation and coding schemes, which e.g. may cause the downlink datatransmissions to fail and be in need of being retransmitted. Thus, abetter scheduling of the downlink data transmissions on the eCCH isenabled, achieving an increasing data throughput in thetelecommunications system.

It should also be noted that some of the embodiments described hereinadvantageously avoids complicating the operations of the schedulingalgorithms in the network node. This is because some of the unsuitableMCSs that are avoided are located in the middle of the MCS index range.This is otherwise known to complicate the operations of the schedulingalgorithms in the network node.

Another advantage of some embodiments described herein is that theyallow peak data rates to be achieved in an LTE system configured witheCCHs.

A further advantage of some embodiments described herein is that theyfurther allow fine-tuning of code rates to achieve a better systemperformance.

FIG. 16 depicts a telecommunications system 100 in which embodimentsherein may be implemented. The cellular communications system 100 is awireless communication network such as an LTE, WCDMA, GSM network, any3GPP cellular network, or any cellular network or system.

The telecommunications system 100 comprises a network node 110, whichmay be a base station. The network node 110 serves a cell 115. Thenetwork node 110 may in this example e.g. be an eNB, an eNodeB, or aHome Node B, a Home eNode B, a femto Base Station (BS), a pico BS or anyother network unit capable to serve a user equipment or a machine typecommunication device which are located in the cell 115 in thetelecommunications system 100.

A user equipment 121 is located within the cell 115. The user equipment121 is configured to communicate within the telecommunications system102 via the network node 110 over a radio link 130 when the userequipment 121 is present in the cell 115 served by the network node 110.The user equipment 121 may e.g. be a mobile terminal, a wirelessterminal, a mobile phone, a computer such as e.g. a laptop, a PersonalDigital Assistant (PDA) or a tablet computer, sometimes referred to as asurf plate, with wireless capability, a device equipped with a wirelessinterface, such as a printer or a file storage device or any other radionetwork unit capable of communicating over a radio link in atelecommunications system.

Embodiments of a method in the user equipment 121 will now be describedwith reference to the flowchart depicted in FIGS. 17. The flowchart inFIG. 17 describes a method in the user equipment 121 for determining atransport block size. The transport block size is used by the userequipment 121 in receiving downlink data transmissions from the networknode 110 on an enhanced Control CHannel, eCCH. The user equipment 121and the network node 110 are comprised in a telecommunications system100. The user equipment 121 has access to a table of predeterminedtransport block sizes. The table of predetermined transport block sizesmay, for example, be the TBS table 7.1.7.2.1-1 in the standardspecification 3GPP TS 36.213 “Physical Layer Procedures”.

FIG. 17 is an illustrating example of exemplary actions or operationswhich may betaken by a user equipment 121. It should be appreciated thatthe flowchart diagram is provided merely as an example and that the userequipment 121 may be configured to perform any of the exemplary actionsor operations provided herein. It should be appreciated that the actionsor operations illustrated below are merely examples, thus it is notnecessary for all the actions or operations to be performed. It shouldalso be appreciated that the actions or operations may be performed inany combination or suitable order. The flowchart in FIG. 17 comprisesthe following actions, and may also be implemented for any of the aboveand below mentioned embodiments or in any combination with those.

Action 1701

In this optional action, the user equipment 121 may determine acondition. The presence of the condition triggers the calculating of anindicator, e.g. the indicator N_(PRB) described in Action 1703. In otherwords, the user equipment 121 may determine a condition to trigger thecalculation of a modulated transport block size. This means that theuser equipment 121 may determine a condition, a presence of saidcondition triggering the calculating of the indicator N_(PRB).

In some embodiments, the condition may be that the user equipment 121receives communications and/or a communication request on an eCCH fromthe network node 110. The eCCH may here be located in a userequipment-specific search space. In some embodiments, the user equipment121 may determine a transport block size according to actions describedbelow, when the user equipment 121 receives the downlink eCCH in theUE-specific search space. According to these embodiments, this meansthat the user equipment 121 may optionally not determine a transportblock size according to actions described below, when it receives thedownlink eCCH in the common search space.

In some embodiments, the condition may be that the user equipment 121receives a request from the network node 110 to calculate the modulatedtransport block size. It should be noted that the calculation of themodulated transport block size may be considered as determining orobtaining the modulated transport block size.

Action 1702

This is an optional action. The user equipment 121 may here receive aPRB offset value O_(PRB), or a PRB adjustment factor A_(PRB).Alternatively, the user equipment 121 may be configured with values forthe PRB offset value O_(PRB), or the PRB adjustment factor A_(PRB).

In some embodiments, the user equipment 121 may receive the PRB offsetvalue O_(PRB), or the PRB adjustment factor A_(PRB), before the userequipment 121 starts to receive downlink data transmissions on the eCCHfrom the network node 110.

In some embodiments, the user equipment 121 may receive the PRB offsetvalue O_(PRB), or the PRB adjustment factor A_(PRB), in an RRC messagecomprised in a downlink transmission from the network node 110 scheduledin a Physical Downlink Control CHannel, PDCCH. This means that the PRBoffset value(s) O_(PRB) or the PRB adjustment factor(s) A_(PRB) may beconfigured with Radio Resource Control (RRC) signalling.

In other words, the user equipment 121 may retrieve computationalparameters. In some embodiments, the user equipment 121 may retrieve thecomputational parameters from the received request, communicationrequest or communication from the network node 110. This means that thecommunication request may comprise the PRB offset value O_(PRB), or thePRB adjustment factor A_(PRB). In some embodiments, the user equipment121 may retrieve the computational parameters using downlink eCCHs. Insome embodiments, different user equipments 121 may be configured withdifferent PRB offset values O_(PRB) or different the PRB adjustmentfactors A_(PRB) via dedicated control signalling.

In some embodiments, the PRB offset value(s) O_(PRB) or PRB adjustmentfactor(s) A_(PRB) may also be given by a fixed value(s) in the userequipment 121. The fixed values of the PRB offset value(s) O_(PRB) orPRB adjustment factor(s) A_(PRB) may be used, for example, if the userequipment 121 is configured to use eCCH for at least one of thefollowing downlink assignment, uplink grants, or power control.

In some embodiments, the user equipment 121 may apply default PRB offsetvalues O_(PRB), or adjustment factors A_(PRB), that do not requireexplicit signalling from the network node 110, but are determined by theuser equipment 121 based on e.g. the configured transmit mode, rank,CFI, number of CRS ports, number of configured PRB pairs for eCCH, etc.If the PRB offset(s) O_(PRB) or adjustments factors A_(PRB) aresignalled to the user equipment 121 by the network node 110, the defaultPRB offset values O_(PRB) or adjustment factors A_(PRB) may beoverridden through RRC signalling.

In some embodiments, the user equipment 121 may give a higher priorityto the PRB offset values O_(PRB), or the PRB adjustment factors A_(PRB),that are received in a communication request from the network node 110,than to the PRB offset values O_(PRB), or the PRB adjustment factorsA_(PRB), retrieved by the user equipment 121.

In some embodiments, more than one user equipment 121 may be configuredwith an identical PRB offset value O_(PRB) or identical PRB adjustmentfactor via control signals addressing the more than one user equipment121.

In summary, this action means that the user equipment 121 may retrievethe PRB offset value O_(PRB), or the PRB adjustment factor A_(PRB), usedin calculating the indicator N_(PRB) described in Action 1703.

Action 1703

In this action, the user equipment 121 calculates an indicator N_(PRB)based on the total number of PRBs allocated to the downlink datatransmission N′_(PRB), and based on an PRB offset value O_(PRB) or a PRBadjustment factor A_(PRB). This is performed in order to achieve a moresuitable indicator than total number of PRBs allocated to the downlinkdata transmission N′_(PRB) in the actual TBS determination. It should benoted that the calculation of the indicator N_(PRB) may be considered asdetermining or obtaining the indicator N_(PRB).

In other words, the user equipment 121 may dynamically calculate amodulated transport block size. This means that the user equipment 121uses at least one PRB offset value O_(PRB), or at least one PRBadjustment factor A_(PRB), in the actual TBS determination. The PRBoffset value(s) O_(PRB) may, for example, be a positive or a negativenumber(s). The adjustment factor A_(PRB) may, for example, be larger orsmaller than 1.

In the embodiments below, the user equipment 121 first calculates thetotal number of allocated PRBs, N′_(PRB), based on the PRB resourceallocation comprised in the downlink control and the procedure providedin the specification.

In some embodiments, the user equipment 121 applies a PRB offset valueO_(PRB) in the determination of the transport block size in allsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the indicator N_(PRB) maybe calculated using the equation (Eq. 1) below:

N _(PRB)=min{max{└N′ _(PRB)×0.75┘+O _(PRB),1},110}  (Eq. 1)

Otherwise, in this case, the indicator N_(PRB) may be calculated usingthe equation (Eq. 2) below:

N _(PRB)=min{max{N′ _(PRB) +O _(PRB),1},110}  (Eq. 2)

In some embodiments, the user equipment 121 applies a PRB offset valueO_(PRB) in the determination of TBS only in non-special subframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the indicator N_(PRB) iscalculated using the equation (Eq. 3) below:

N _(PRB)=max{└N′ _(PRB)×0.75┘,1}  (Eq. 3)

Otherwise, in this case, the indicator N_(PRB) may be calculated usingthe equation (Eq. 4) below:

N _(PRB)−min{max{N′ _(PRB) +O _(PRB),1},110}  (Eq. 4)

Here, in some embodiments, the user equipment 121 may apply differentPRB offset values O_(PRB) in the determination of TBS in differentsubframes based on the subframe number. This means that the userequipment 121 may comprise more than one PRB offset value O_(PRB) andalso may apply different PRB offset values O_(PRB) in differentsubframes based on the subframe number of the subframes in the differentsubframes.

In some embodiments, the user equipment 121 may apply different PRBoffset values O_(PRB) in different subframes based on if there areadditional reference signals present. Examples of such additionalreference signals may be CSI reference signals or positioning referencesignals. Other examples of such additional reference signals may be thatthe subframe comprises PDCCH, PHICH, PCFICH, PSS, SSS or PBCH. Thismeans that the user equipment 121 may comprise more than one PRB offsetvalue O_(PRB) and further may apply different PRB offset values O_(PRB)in different subframes based on the presence of additional signals.

It should also be noted that this calculation may be applied when theN′_(PRB) value is greater than the PRB threshold value, T_(PRB). Thismeans that, in some embodiments, the calculating which applies a PRBoffset value O_(PRB) in the determination of the transport block size isperformed if N′_(PRB) is larger than a physical resource block thresholdT_(PRB).

This may advantageously be used in order to reach certain peak rates.For instance, the PRB offset value O_(PRB) applies only when N′_(PRB) isequal to the total number of DL RBs in the system bandwidth minus oneand the PRB offset value O_(PRB) is then plus one. This ensures that thepeak rate can be achieved when scheduled from eCCH.

In some embodiments, the user equipment 121 applies a PRB adjustmentfactor A_(PRB) in the determination of the transport block size in allsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the indicator N_(PRB) maybe calculated using the equation (Eq. 5) below:

N _(PRB)=min{max{└N′ _(PRB)×0.75×A _(PRB)┘,1},110}  (Eq. 5)

Otherwise, in this case, the indicator N_(PRB) may be calculated usingthe equation (Eq. 6) below:

N _(PRB)=min{max{└N′ _(PRB) ×A _(PRB)┘,1},110}  (Eq. 6)

In some embodiments, the user equipment 121 applies a PRB adjustmentfactor A_(PRB) in the determination of TBS only in non-specialsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the indicator N_(PRB) maybe calculated using the equation (Eq. 7) below:

N _(PRB)=max{└N′ _(PRB)×0.75┘,1}  (Eq. 7)

Otherwise, in this case, the indicator N_(PRB) may be calculated usingthe equation (Eq. 8) below:

N _(PRB)=min{max{└N′ _(PRB) ×A _(PRB)┘,1},110}  (8)

Here, in some embodiments, the user equipment 121 may apply differentPRB offset values O_(PRB) in the determination of TBS in differentsubframes based on the subframe number. This means that the userequipment 121 may comprise more than one PRB adjustment factor A_(PRB),and also may apply different PRB adjustment factors A_(PRB) in differentsubframes based on the subframe number of the subframes in the differentsubframes.

In some embodiments, the user equipment 121 may apply different PRBoffset values O_(PRB) in different subframes based on if there areadditional reference signals present. Examples of such additionalreference signals may be CSI reference signals or positioning referencesignals. Other examples of such additional reference signals may be thatthe subframe comprises PDCCH, PHICH, PCFICH, PSS, SSS or PBCH. Thismeans that the user equipment 121 comprises more than one PRB adjustmentfactor A_(PRB), and further may apply different PRB adjustment factorsA_(PRB), in different subframes based on the presence of additionalsignals.

It should also be noted that this calculation may be applied when theN′_(PRB) value is greater than the PRB threshold value, T_(PRB). Thismeans that, in some embodiments, the calculating which applies a PRBadjustment factor A_(PRB) in the determination of the transport blocksize is performed if N′_(PRB) is larger than a physical resource blockthreshold T_(PRB). This may advantageously be used in order to reachcertain peak rates. For instance, the PRB adjustment factor A_(PRB)applies only when N′_(PRB) is equal to the total number of DL RBs in thesystem bandwidth minus one and the PRB adjustment factor A_(PRB) is thenplus one. This ensures that the peak rate can be achieved when scheduledfrom eCCH.

Action 1704

In this action, the user equipment 121 determines the transport blocksize from the table of predetermined transport block sizes based on atleast the calculated indicator N_(PRB).

In some embodiments, the user equipment 121 applies a PRB offset valueO_(PRB) in the determination of the transport block size in allsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the transport block sizeis determined by using the indicator N_(PRB) calculated using theequation Eq. 1 in Action 1703 as the column indicator in the table ofpredetermined transport block sizes, e.g. the transport block size table7.1.7.2.1-1 in the in the standard specification 3GPP TS 36.213“Physical Layer Procedures”.

Otherwise, in this case, the transport block size is determined by usingthe indicator N_(PRB) that is calculated using the equation Eq. 2 inAction 1703 as the column indicator in the table of predeterminedtransport block sizes, e.g. the transport block size table 7.1.7.2.1-1in the in the standard specification 3GPP TS 36.213 “Physical LayerProcedures”.

In some embodiments, the user equipment 121 applies a PRB offset valueO_(PRB) in the determination of TBS only in non-special subframes. Inthis case, if the transport block is transmitted in DwPTS of the specialsubframe in the frame structure, then the transport block size isdetermined by using the indicator N_(PRB) is calculated using theequation Eq. 3 in Action 1703 as the column indicator in the table ofpredetermined transport block sizes, e.g. the transport block size table7.1.7.2.1-1 in the in the standard specification 3GPP TS 36.213“Physical Layer Procedures”.

Otherwise, in this case, the transport block size is determined by usingthe indicator N_(PRB) is calculated using the equation Eq. 4 in Action1703 as the column indicator in the table of predetermined transportblock sizes, e.g. the transport block size table 7.1.7.2.1-1 in the inthe standard specification 3GPP TS 36.213 “Physical Layer Procedures”.

In some embodiments, the user equipment 121 applies a PRB adjustmentfactor A_(PRB) in the determination of the transport block size in allsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the transport block sizeis determined by using the indicator N_(PRB) is calculated using theequation Eq. 5 in Action 1703 as the column indicator in the table ofpredetermined transport block sizes, e.g. the transport block size table7.1.7.2.1-1 in the in the standard specification 3GPP TS 36.213“Physical Layer Procedures”.

Otherwise, in this case, the transport block size is determined by usingthe indicator N_(PRB) is calculated using the equation Eq. 6 in Action1703 as the column indicator in the table of predetermined transportblock sizes, e.g. the transport block size table 7.1.7.2.1-1 in the inthe standard specification 3GPP TS 36.213 “Physical Layer Procedures”.

In some embodiments, the user equipment 121 applies a PRB adjustmentfactor A_(PRB) in the determination of TBS only in non-specialsubframes.

In this case, if the transport block is transmitted in DwPTS of thespecial subframe in the frame structure, then the transport block sizeis determined by using the indicator N_(PRB) is calculated using theequation Eq. 7 in Action 1703 as the column indicator in the table ofpredetermined transport block sizes, e.g. the transport block size table7.1.7.2.1-1 in the in the standard specification 3GPP TS 36.213“Physical Layer Procedures”.

Otherwise, in this case, the transport block size is determined by usingthe indicator N_(PRB) is calculated using the equation Eq. 8 in Action1703 as the column indicator in the table of predetermined transportblock sizes, e.g. the transport block size table 7.1.7.2.1-1 in the inthe standard specification 3GPP TS 36.213 “Physical Layer Procedures”.

It should also be noted that according to some embodiments, if a userequipment 121 is configured to use eCCH for e.g. downlink assignments,uplink grants and power control, the user equipment 121 may determineits allocated transport block size N_(PRB) at least for some assignmentsor grants by using at least one PRB offset value, O_(PRB) or at leastone PRB adjustment factor, A_(PRB).

Action 1705

In this optional action, the user equipment 121 may receive downlinkdata transmissions using the determined transport block size. In otherwords, the user equipment 121 may receive the downlink data using themodulated transport block size.

Embodiments of a method in the network node 110 will now be describedwith reference to the flowchart depicted in FIGS. 18. The flowchart inFIG. 18 describes a method in the network node 110 for determining atransport block size. The transport block size is used by the networknode 110 in transmitting downlink data transmissions to the userequipment 121 on an enhanced control channel, eCCH. The network node 110and the user equipment 121 are comprised in a telecommunications system.The network node 110 has access to a table of predetermined transportblock sizes. The table of predetermined transport block sizes may, forexample, be the TBS table 7.1.7.2.1-1 in the standard specification 3GPPTS 36.213 “Physical Layer Procedures”.

FIG. 18 is an illustrating example of detailed exemplary actions oroperations which may be taken by the network node 110. It should beappreciated that the flowchart diagram is provided merely as an exampleand that the network node 110 may be configured to perform any of theexemplary actions or operations provided herein. It should beappreciated that the actions or operations illustrated below are merelyexamples, thus it is not necessary for all the actions or operations tobe performed. It should also be appreciated that the actions oroperations may be performed in any combination. Hence, the flowchart inFIG. 18 comprises the following actions, and may also be implemented forany of the above and below mentioned embodiments or in any combinationwith those.

Action 1801

In this optional action, the network node 110 may transmit acommunication request to the user equipment 121, which communicationrequest comprises the PRB offset value O_(PRB), or the PRB adjustmentfactor A_(PRB).

Alternatively, in some embodiments, the network node 110 may transmitthe PRB offset value O_(PRB), or the PRB adjustment factor A_(PRB), inan RRC message comprised in a downlink transmission scheduled in aPDCCH. This means that the PRB offset value(s) O_(PRB) or the PRBadjustment factor(s) A_(PRB) may be configured by the network node 110with RRC signalling.

In some embodiments, the network node 110 may configure different userequipments with different PRB offset values O_(PRB) or different the PRBadjustment factors A_(PRB) via dedicated control signalling. Also, insome embodiments, the network node 110 may configure more than one userequipment 121 with an identical PRB offset value O_(PRB) or identicalPRB adjustment factor via control signals addressing the more than oneuser equipment 121.

In some embodiments, the network node 110 may transmit the PRB offsetvalue O_(PRB), or the PRB adjustment factor A_(PRB), to the userequipment 121 before the user equipment 121 starts to receive downlinkdata transmissions on the eCCH from the network node 110. In someembodiments, the network node 110 may transmit the communication requestand/or the communication on an eCCH. The eCCH may here be located in auser equipment-specific search space.

In some embodiments, the network node 110 may transmit a request to theuser equipment 121 to calculate the modulated transport block size.

Action 1802

In this action, the network node 110 calculates an indicator N_(PRB)based on the total number of PRBs allocated to the downlink datatransmission N′_(PRB), and based on an PRB offset value O_(PRB), or aPRB adjustment factor A_(PRB). It should be noted that the calculationof the indicator N_(PRB) may be considered as determining or obtainingthe indicator N_(PRB).

These calculations may be performed by the network node 110 in the sameway as described for the user equipment 121 in Action 1703. This meansthat the network node 110 may calculate the indicator N_(PRB) accordingto any one of the equations Eq. 1-8 as described above in Action 1703.In some embodiments, this also means that the network node 110 mayperform the calculations if N′_(PRB) is larger than a physical resourceblock threshold T_(PRB).

Action 1803

In this action, the network node 110 determines the transport block sizefrom the table of predetermined transport block sizes based on at leastthe calculated indicator N_(PRB). The determination may be performed bythe network node 110 in the same way as described for the user equipment121 in Action 1704.

Action 1804

In this action, the network node 110 transmit, to the user equipment121, downlink data transmissions using the determined transport blocksize. In other words, the user equipment 121 may transmit downlink datausing the modulated transport block size.

The example embodiments presented herein may be utilized in a radionetwork, which may further comprise network nodes, such as, a basestation 110, as illustrated in FIG. 19. The radio network may alsocomprise a user equipment 121, as illustrated in 20. It should beappreciated that the examples provided in FIGS. 19 and 20 are shownmerely as non-limiting examples. According to the example embodiments,the network node 110 and user equipment 121 may be any other node asdescribed in the examples provided in the above sections.

As shown in FIG. 19, the example network node 110 may compriseprocessing circuitry 1903, a memory 1902, radio circuitry 1901, and atleast one antenna. The processing circuitry 1903 may comprise RFcircuitry and baseband processing circuitry (not shown). In particularembodiments, some or all of the functionality described above as beingprovided by a mobile base station, a base station controller, a relaynode, a NodeB, an enhanced NodeB, positioning node, and/or any othertype of mobile communications node may be provided by the processingcircuitry 1903 executing instructions stored on a computer-readablemedium, such as the memory 1902 shown in FIG. 19. Alternativeembodiments of the network node 110 may comprise additional componentsresponsible for providing additional functionality, comprising any ofthe functionality identified above and/or any functionality necessary tosupport the solution described above. In other example embodiments, anetwork node may be not equipped with a radio interface or radiocircuitry 1901.

It should also be appreciated that the processing circuitry, or anyother hardware and/or software unit configured to execute operationsand/or commands, of the network node 110 illustrated in FIG. 19 may beconfigured to configure to calculate a modified transport block sizeand/or provide computational parameters to be used in the calculation ofa modified block size as described in the exemplary embodiments providedabove.

An example of a user equipment 121 is provided in FIG. 14. The exampleuser equipment 121 may comprise processing circuitry 2002, a memory2003, radio circuitry 2001, and at least one antenna. The radiocircuitry 2001 may comprise RF circuitry and baseband processingcircuitry (not shown). In particular embodiments, some or all of thefunctionality described above as being provided by mobile communicationdevices or other forms of wireless device may be provided by theprocessing circuitry 2002 executing instructions stored on acomputer-readable medium, such as the memory 2003 shown in FIG. 20.Alternative embodiments of the user equipment 121 may compriseadditional components responsible for providing additionalfunctionality, comprising any of the functionality identified aboveand/or any functionality necessary to support the solution describedabove.

It should be appreciated that the processing circuitry (or any otherhardware and/or software unit configured to execute operations and/orcommands) of the user equipment 121 may be configured to calculate amodified transport block size. The user equipment may be furtherconfigured to perform any of the exemplary operations described above.

To perform the method actions for determining a transport block size,the network node 110 comprises the following arrangement depicted inFIG. 19. FIG. 19 shows a schematic block diagram of embodiments of thenetwork node 110.

The transport block size is used by the network node 110 in transmittingdownlink data transmissions to the user equipment 121 on an eCCH. Thenetwork node 110 and the user equipment 121 are comprised in atelecommunications system 100. The network node 110 has access to atable of predetermined transport block sizes.

The network node 110 may comprise a radio circuitry 1901. The radiocircuitry 1901 may be configured to transmit, to the user equipment 121,downlink data transmissions using the determined transport block size.The radio circuitry 1901 may also be configured to transmit acommunication request to the user equipment 121. The communicationrequest may comprise the PRB offset value O_(PRB), or the PRB adjustmentfactor A_(PRB).

The network node 110 comprises a processing circuitry 1903 configured tocalculate an indicator N_(PRB) based on the total number of PRBsallocated to the downlink data transmission N′_(PRB), and on an PRBoffset value O_(PRB), or a PRB adjustment factor A_(PRB). It should benoted that the calculation of the indicator N_(PRB) may be considered asdetermining or obtaining the indicator N_(PRB). The processing circuitry1903 is further configured to determine the transport block size fromthe table of predetermined transport block sizes based on at least thecalculated indicator N_(PRB).

The processing circuitry 1903 may further be configured to calculate theindicator N_(PRB) according to any one of the equations Eq. 1-8 asdescribed above. Also, the processing circuitry 1903 may further beconfigured to perform the calculations if N′_(PRB) is larger than aphysical resource block threshold T_(PRB).

To perform the method actions for determining a transport block size,the user equipment 121 comprises the following arrangement depicted inFIG. 20. FIG. 20 shows a schematic block diagram of embodiments of theuser equipment 121.

The transport block size is used by the user equipment 121 in receivingdownlink data transmissions from a network node 110 on an enhancedControl CHannel, eCCH. The user equipment 121 and the network node 110are comprised in a telecommunications system 100. The user equipment 121has access to a table of predetermined transport block sizes.

The user equipment 121 may further comprise a radio circuitry 2001. Theradio circuitry 2101 may be configured to receive downlink datatransmissions using the determined transport block size.

The user equipment 121 comprises a processing circuitry 2002 configuredto calculate an indicator N_(PRB) based on the total number of PRBsallocated to the downlink data transmission N′_(PRB), and based on anPRB offset value O_(PRB) or a PRB adjustment factor A_(PRB). It shouldbe noted that the calculation of the indicator N_(PRB) may be consideredas determining or obtaining the indicator N_(PRB). The processingcircuitry 2002 is further configured to determine the transport blocksize from the table of predetermined transport block sizes based on atleast the calculated indicator N_(PRB).

The processing circuitry 2002 may further be configured to determine acondition, a presence of said condition triggering the calculating ofthe indicator N_(PRB). The condition may be receiving communicationsand/or a communication request on the eCCH. The eCCH may be located in auser equipment-specific search space. The condition may also bereceiving a communication request from the network node 110 to calculatethe transport block size. The communication request may comprise the PRBoffset value O_(PRB), or the PRB adjustment factor A_(PRB).

The processing circuitry 2002 may further be configured to retrieve thePRB offset value O_(PRB), or the PRB adjustment factor A_(PRB), to beused in the calculation. The processing circuitry 2102 may further beconfigured to receive the PRB offset value O_(PRB), or the PRBadjustment factor A_(PRB), before the user equipment 121 starts toreceive downlink data transmissions on the eCCH from the network node110, or receive the PRB offset value O_(PRB), or the PRB adjustmentfactor A_(PRB), in an RRC message comprised in a downlink transmissionfrom the network node 110 scheduled in a Physical Downlink ControlCHannel, PDCCH.

The processing circuitry 2002 may further be configured to calculate theindicator N_(PRB) according to any one of the equations Eq. 1-8 asdescribed above.

The processing circuitry 2002 may further be configured to applydifferent PRB offset values O_(PRB), or PRB adjustment factors A_(PRB),in different subframes based on the subframe number, when the userequipment 121 comprises more than one PRB offset value O_(PRB), or PRBadjustment factor A_(PRB) Also, when the user equipment 121 comprisesmore than one PRB offset value O_(PRB), or adjustment factor A_(PRB),the processing circuitry 2002 may further be configured to applydifferent PRB offset values O_(PRB), or PRB adjustment factors A_(PRB),in different subframes based on the presence of additional referencesignals.

The processing circuitry 2002 may also be configured to perform thecalculations if N′_(PRB) is larger than a physical resource blockthreshold T_(PRB). Furthermore, the processing circuitry 2002 may beconfigured to give PRB offset values O_(PRB), or the PRB adjustmentfactors A_(PRB), received in a communication request from the networknode 110 a higher priority over PRB offset values O_(PRB), or the PRBadjustment factors A_(PRB), retrieved by the user equipment 121.

The description of the example embodiments provided herein have beenpresented for purposes of illustration. The description is not intendedto be exhaustive or to limit example embodiments to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of various alternativesto the provided embodiments. The examples discussed herein were chosenand described in order to explain the principles and the nature ofvarious example embodiments and its practical application to enable oneskilled in the art to utilize the example embodiments in various mannersand with various modifications as are suited to the particular usecontemplated. The features of the embodiments described herein may becombined in all possible combinations of methods, apparatus, modules,systems, and computer program products. It should be appreciated thatthe example embodiments presented herein may be practiced in anycombination with each other.

It should be noted that the word “comprising” does not necessarilyexclude the presence of other elements or steps than those listed andthe words “a” or “an” preceding an element do not exclude the presenceof a plurality of such elements. It should further be noted that anyreference signs do not limit the scope of the claims, that the exampleembodiments may be implemented at least in part by means of bothhardware and software, and that several “means”, “units” or “devices”may be represented by the same item of hardware.

A “device” as the term is used herein, is to be broadly interpreted toinclude a radiotelephone having ability for Internet/intranet access,web browser, organizer, calendar, a camera (e.g., video and/or stillimage camera), a sound recorder (e.g., a microphone), and/or globalpositioning system (GPS) receiver; a personal communications system(PCS) terminal that may combine a cellular radiotelephone with dataprocessing; a personal digital assistant (PDA) that can include aradiotelephone or wireless communication system; a laptop; a camera(e.g., video and/or still image camera) having communication ability;and any other computation or communication device capable oftransceiving, such as a personal computer, a home entertainment system,a television, etc.

Although the description is mainly given for a user equipment, asmeasuring or recording unit, it should be understood by the skilled inthe art that “user equipment” is a non-limiting term which means anywireless device or node capable of receiving in DL and transmitting inUL (e.g. PDA, laptop, mobile, sensor, fixed relay, mobile relay or evena radio base station, e.g. femto base station).

A cell is associated with a radio node, where a radio node or radionetwork node or eNodeB used interchangeably in the example embodimentdescription, comprises in a general sense any node transmitting radiosignals used for measurements, e.g., eNodeB, macro/micro/pico basestation, home eNodeB, relay, beacon device, or repeater. A radio nodeherein may comprise a radio node operating in one or more frequencies orfrequency bands. It may be a radio node capable of CA. It may also be asingle- or multi-RAT node. A multi-RAT node may comprise a node withco-located RATs or supporting multi-standard radio (MSR) or a mixedradio node.

The various example embodiments described herein are described in thegeneral context of method steps or processes, which may be implementedin one aspect by a computer program product, embodied in acomputer-readable medium, including computer-executable instructions,such as program code, executed by computers in networked environments. Acomputer-readable medium may include removable and non-removable storagedevices including, but not limited to, Read Only Memory (ROM), RandomAccess Memory (RAM), compact discs (CDs), digital versatile discs (DVD),etc. Generally, program modules may include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types. Computer-executableinstructions, associated data structures, and program modules representexamples of program code for executing steps of the methods disclosedherein. The particular sequence of such executable instructions orassociated data structures represents examples of corresponding acts forimplementing the functions described in such steps or processes.

The embodiments herein are not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused. Therefore, the above embodiments should not be construed aslimiting.

ABBREVIATIONS

-   ACK Acknowledgement-   ARQ Automatic Repeat Request-   CA Carrier Aggregation-   CAZAC Constant Amplitude Zero Auto Correlation-   CC Component Carrier-   CCE Control Channel Element-   CFI Control Format Indicator-   CIF Carrier Indicator Field-   C-RNTI Cell radio-network temporary identifier-   CRS Common Reference Symbols-   CSI Channel State Information-   DCI Downlink Control Information-   DL Downlink-   DMRS Demodulation Reference Symbols-   eCCH enhanced Control CHannel-   ePDCCH enhanced PDCCH-   HARQ Hybrid Automatic Repeat Request-   LTE Long term evolution-   MAC Medium Access Control-   MIMO Multiple-Input Multiple-Output-   NACK Non Acknowledgement-   OFDM Orthogonal Frequency Division Multiple Access-   PCC Primary Component Carrier-   PDCCH Physical Downlink Control Channel-   PDSCH Physical Downlink Shared Channel-   PUCCH Physical Uplink Control Channel-   RB or PRB Resource block-   RE Resource Element-   RNTI Radio-network temporary identifier-   RS Reference Signal-   SCC Secondary Component Carrier-   SINR Signal-to-Norse Ratio-   TPC Transmit Power Control-   UE User equipment-   UL Uplink

1-50. (canceled)
 51. A method in a user equipment for determining atransport block size, which transport block size is used by the userequipment in receiving downlink data transmissions from a network nodewhich are frequency multiplexed with an enhanced Control Channel, eCCH,the user equipment and the network node being comprised in atelecommunications system, which user equipment has access to a table ofpredetermined transport block sizes for different number of allocatedradio resource blocks, PRBs, the method comprising determining thetransport block size from the table of predetermined transport blocksizes based on at least an indicator N_(PRB) defined based on a totalnumber of PRBs allocated to the downlink data transmission N′_(PRB) andbased on a positive PRB offset value O_(PRB).
 52. The method accordingto claim 51, further comprising: receiving downlink data transmissionsusing the determined transport block size.
 53. The method according toclaim 51, wherein the step of determining is performed when the eCCH andthe data transmission are scheduled in the allocated radio resourceblocks.
 54. The method according to claim 51, the method comprising:determining the transport block size from the table of determinedtransport block sizes based on the indicator N_(PRB) equalling the totalnumber of PRBs allocated to the downlink data transmission N′_(PRB) whenthe eCCE is not scheduled in the allocated radio resource blocks. 55.The method according to claim 51, wherein the eCCH is received in a userequipment-specific search space.
 56. The method according to claim 51,the method comprising calculating the indicator N_(PRB) based on thetotal number of PRBs allocated to the downlink data transmissionN′_(PRB), and based on the positive PRB offset value O_(PRB), whereinthe step of determining (1704) the transport block size from the tableof predetermined transport block sizes is performed based on at leastthe indicator N_(PRB).
 57. The method according to claim 56, wherein thecalculating further comprises retrieving the PRB offset value O_(PRB),used in calculating the indicator N_(PRB).
 58. The method according toclaim 51, further comprising receiving the PRB offset value O_(PRB),before the user equipment starts to receive downlink data transmissionsmultiplexed in frequency with the eCCH from the network node; orreceiving the PRB offset value O_(PRB), in an RRC message comprised in adownlink transmission from the network node scheduled by a PhysicalDownlink Control CHannel PDCCH.
 59. The method according to claim 51,wherein the indicator N_(PRB) is defined by the total number of PRBsallocated to the downlink data transmission N′_(PRB) plus the positivePRB offset value O_(PRB).
 60. A user equipment for determining atransport block size, which transport block size is used by the userequipment in receiving downlink data transmissions from a network nodewhich are frequency multiplexed with an enhanced Control CHannel, eCCH,the user equipment and the network node being comprised in atelecommunications system, which user equipment has access to a table ofpredetermined transport block sizes for different number of allocatedradio resource blocks, PRBs, the user equipment being adapted todetermine the transport block size from the table of predeterminedtransport block sizes based on at least an indicator N_(PRB) definedbased on a total number of PRBs allocated to the downlink datatransmission N′_(PRB) and based on a positive PRB offset value O_(PRB).61. The user equipment according to claim 60, wherein the user equipmentis further adapted to: receive downlink data transmissions using thedetermined transport block size.
 62. The user equipment according toclaim 60, wherein the user equipment is adapted to perform the step ofdetermining when the eCCH and the data transmission are scheduled in theallocated radio resource blocks.
 63. The user equipment according toclaim 60, wherein the user equipment is further adapted to: determinethe transport block size from the table of determined transport blocksizes based on the indicator N_(PRB) equalling the total number of PRBsallocated to the downlink data transmission N′_(PRB) when the eCCE isnot scheduled in the allocated radio resource blocks.
 64. The userequipment according to claim 60, wherein the eCCH is received in a userequipment-specific search space.
 65. The user equipment according toclaim 60, wherein the user equipment is further adapted, to: calculatethe indicator N_(PRB) based on the total number of PRBs allocated to thedownlink data transmission N′_(PRB), and based on the positive PRBoffset value O_(PRB), wherein the user equipment is adapted to performthe step of determining (1704) the transport block size from the tableof predetermined transport block sizes based on at least the indicatorN_(PRB).
 66. The user equipment according to claim 65, wherein the userequipment adapted to calculate the indicator N_(PRB) based on the totalnumber of PRBs allocated to the downlink data transmission N′_(PRB), andbased on the positive PRB offset value O_(PRB) comprises the userequipment further adapted to: retrieve the PRB offset value O_(PRB),used in calculating the indicator N_(PRB).
 67. The user equipmentaccording to claim 60, wherein the user equipment is further adapted to:receive the PRB offset value O_(PRB), before the user equipment startsto receive downlink data transmissions multiplexed in frequency with theeCCH from the network node; or receive the PRB offset value O_(PRB), inan RRC message comprised in a downlink transmission from the networknode scheduled by a Physical Downlink Control CHannel, PDCCH.
 68. Theuser equipment according to claim 60, wherein the indicator N_(PRB) isdefined by the total number of PRBs allocated to the downlink datatransmission N′_(PRB) plus the positive PRB offset value O_(PRB).
 69. Amethod in a network node for determining a transport block size, whichtransport block size is used by the network node in transmittingdownlink data transmissions to the user equipment which are multiplexedin frequency with an enhanced control channel, eCCH, the network nodeand the user equipment being comprised in a telecommunications system,which network node has access to a table of predetermined transportblock sizes for a number of allocated radio resource blocks, PRBs, themethod comprising determining the transport block size from the table ofpredetermined transport block sizes based on at least an indicatorN_(PRB) defined based on a total number of PRBs allocated to thedownlink data transmission N′_(PRB) and based on a positive PRB offsetvalue O_(PRB).
 70. The method according to claim 69, further comprisingtransmitting, to the user equipment, downlink data transmissions usingthe determined transport block size.
 71. The method according to claim69, wherein the step of determining is performed when the eCCH and thedata transmission are scheduled in the allocated radio resource blocks.72. The method according to claim 69, the method comprising determiningthe transport block size from the table of determined transport blocksizes based on the indicator N_(PRB) equalling the total number of PRBsallocated to the downlink data transmission N′_(PRB) when the eCCE isnot scheduled in the allocated radio resource blocks.
 73. The methodaccording to claim 69, the method comprising: sending the PRB offsetvalue O_(PRB), before the user equipment starts to receive downlink datatransmissions multiplexed in frequency with the eCCH from the networknode; or sending the PRB offset value O_(PRB), in an RRC messagecomprised in a downlink transmission from the network node scheduled bya Physical Downlink Control CHannel, PDCCH.
 74. The method according toclaim 69, wherein the indicator N_(PRB) is defined by the total numberof PRBs allocated to the downlink data transmission N′_(PRB) plus thepositive PRB offset value O_(PRB).
 75. The method according to claim 69,the method comprising calculating the indicator N_(PRB) based on thetotal number of PRBs allocated to the downlink data transmissionN′_(PRB) and based on the positive PRB offset value O_(PRB), wherein thedetermining the transport block size from the table of predeterminedtransport block sizes is performed based on at least the indicatorN_(PRB).
 76. A network node for determining a transport block size,which transport block size is used by the network node in transmittingdownlink data transmissions to the user equipment which are multiplexedin frequency with an enhanced control channel, eCCH, the network nodeand the user equipment being comprised in a telecommunications system,which network node has access to a table of predetermined transportblock sizes for a number of allocated radio resource blocks, PRBs, thenetwork node being adapted to determine the transport block size fromthe table of predetermined transport block sizes based on at least anindicator N_(PRB) defined by a total number of PRBs allocated to thedownlink data transmission N′_(PRB) and on a positive PRB offset valueO_(PRB).
 77. The network node according to claim 76, wherein the networknode is further adapted to: transmit, to the user equipment, downlinkdata transmissions using the determined transport block size.
 78. Thenetwork node according to claim 76, wherein the network node is adaptedto perform the step of determining when the eCCH and the datatransmission are scheduled in the allocated radio resource blocks. 79.The network node according to claim 76, wherein the network node isfurther adapted to: determine the transport block size from the table ofdetermined transport block sizes based on the indicator N_(PRB)equalling the total number of PRBs allocated to the downlink datatransmission N′_(PRB) when the eCCE is not scheduled in the allocatedradio resource blocks.
 80. The network node according to claim 76,wherein the network node is further adapted to: send the PRB offsetvalue O_(PRB), before the user equipment starts to receive downlink datatransmissions multiplexed in frequency with the eCCH from the networknode; or send the PRB offset value O_(PRB), in an RRC message comprisedin a downlink transmission from the network node scheduled by a PhysicalDownlink Control CHannel, PDCCH.
 81. The network node according to claim76, wherein the indicator N_(PRB) is defined by the total number of PRBsallocated to the downlink data transmission N′_(PRB) plus the positivePRB offset value O_(PRB).
 82. The network node according to claim 76,wherein the network node is further adapted to: calculate the indicatorN_(PRB) based on the total number of PRBs allocated to the downlink datatransmission N′_(PRB) and based on the positive PRB offset valueO_(PRB), wherein the network node is adapted to determine the transportblock size from the table of predetermined transport block sizes basedon at least the indicator N_(PRB).